DC DC voltage boost converter

ABSTRACT

A high-output ratio DC DC converter supplies at least two regulated output voltages, a positive voltage Vs+ and a negative voltage Vs− from a direct current voltage Vin applied at the input, by means of two voltage boost structures with pairs of switches SBp 1,  SHp 1,  and groups of input capacitors Gin 1  and output capacitors Gout 1,  controlled by an inductive stage with inductance Lin and controlled switch M, a level translator circuit with capacitor Ct and direct diode Dt being provided between the said inductive stage and the structure supplying the negative output voltage.

RELATED APPLICATIONS

The present application is based on, and claims priority from, FrenchApplication Number 06 10605, filed Dec. 5, 2006, the disclosure of whichis hereby incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The present invention relates to a direct current direct current or DCDC converter, of the voltage boost type, making it possible to obtain adirect current output voltage of a higher value than the supply directcurrent voltage applied at the input. The field of application relatesto the low cost and high performance conversion of energy, in particularwith very high output ratio. Such DC DC converters are in particularused in the aviation field to generate high level electric voltages, tosupply electronic devices, from a common low voltage supply generator.

A DC DC voltage boost converter is an uninsulated switched-modeconverter, that comprises an input inductor connected between a directcurrent voltage supply line and the earth, through a controlled switch,typically a switch-controlled transistor, and one or more voltage booststages.

When the aim is to obtain high conversion rates, with a high outputratio and high reliability and service life, it is necessary to defineparticular topologies, particularly for managing the stress due to thehigh voltages and the currents generated.

Also in certain applications, such as aviation, the aim is to obtain alow cost and high performance DC DC energy conversion, in particular ata very high output ratio, for example at least equal to 5.

BACKGROUND OF THE INVENTION

French patent FR 2 860 660 delivered on 21 Jan. 2006 teaches inparticular of converters whose topology with groups of capacitors makesit possible to spread the stress over the various switches and to obtainvery high voltages, with an optimal output ratio. In a practicalexample, it is possible therefore to obtain an output voltage of theorder of 270 volts from an input voltage of 12 volts, or a boost ratiomuch greater than 5.

SUMMARY OF THE INVENTION

The structure of such a voltage boost converter, for supplying a highpositive voltage according to this prior art is shown in FIG. 1 a.

A generator supplies a direct current voltage Vin to input terminals E1and E2 of the converter.

The converter comprises:

-   -   an input inductor Lin connected in series between the input        terminals E1 and E2 via a switch SB, which periodically places        the input inductor in parallel with the generator.    -   an output capacitor Cout connected in parallel to the output        terminals Out1 and Out2.    -   two pairs of switches P₀ and P₁, associated with an input        capacitor Ce and an output capacitor Cs. Usually Ce=Cs=C.

More precisely, each pair comprises two switches connected in series.The pair P₀ therefore comprises the switches SB and SH connected inseries between the terminal E2 and a connection node A₁. The pair P₁comprises the switches SB₁ and SH₁ connected in series between theconnection node A₁ and the output terminal Out1. The load capacitor Ceis connected in parallel between the connection nodes A₀ and A₂ of theswitches of the two successive pairs P₀ and P₁, A₀ being the connectionnode between the switches SB and SH of the pair P₀ and A₂, theconnection node between the switches SB₁ and SH₁ of the pair P₁.

The output filtering capacitor Cs is connected in parallel to the secondpair P₁, between the node A₁ and the terminal Out1.

The operating principle is briefly as follows:

The switches SB and SB₁ are controlled by the same control signal S2,and the switches SH and SH₁ are controlled by the same control signalS1. The control signals S1 and S2 are such that, in each pair, theswitches are controlled simultaneously, one to an on-state resultingfrom the application at its control input of a first control signal S1,the other to an off-state by the application at its control input of asecond control signal S2 complementing the first. The switches SB andSB₁ are therefore controlled to the on-state (closed) for a time Ton andto the open state for a time Toff, while the switches SH and SH₁ arecontrolled to the on-state (closed) for a time Toff and to the openstate for a time Ton.

Preferably, a recovery inductor Lr₁ is provided in series with theswitch SB1 of the pair P₁, so that the capacitor Ce is in parallel onthe whole series SH, SB₁, Lr₁. This inductor allows an improvement ofthe output ratio of the converter. In these conditions, during theconduction period Ton of the switches SB and SB₁ (switches SB and SB₁closed), controlled by an active state of the control signal S2, theswitches SH and SH₁ are open. This gives an oscillating circuitcomprising the output capacitor Cout in parallel with the two capacitorsCe and Cs in series with the recovery inductor Lr₁. The recoveryinductor Lr₁ is computed to obtain a resonance of this oscillatingcircuit so that: where Ton=π.(Lr₁.C_(eq))^(1/2) where C_(eq) is theequivalent capacitor of the oscillating circuit namelyC_(eq)=1/(1/Cout+1/Ce+1/Cs).

For an optimal result, Ton is constant and equal to approximately thehalf-period of the resonance frequency of the oscillating circuit.

During the transition from Toff to Ton, the current in the inductor Lr₁is zero, the voltage (Vce+Vcs) at the terminals of the capacitors Ce andCs is less than the average value of Vout and increases while passingthe average value of Vout. The current in the inductor Lr₁ increaseswhile storing magnetic energy, passes a maximum value when (Vce+Vcs)passes the average value of Vout, then decreases to a zero value,corresponding to the end of Ton, returning the energy to the capacitorsCe and Cs. During Toff, the current in the inductor Lr₁ remains zero,the sum of the voltages (Vce+Vcs) decreases because Ce and Cs aretraversed by the current of the inductor Lin, then the cycle beginsagain at the beginning of Ton.

FIG. 1 b represents the “negative” version of the voltage boostconverter of FIG. 1 a, that is to say by which a boosted negativevoltage Vout is obtained at the output. The converter of FIG. 1 b, ofthe same structure as that of FIG. 1 a, is supplied by a generator Esupplying a negative potential Vin between the input terminals E1 andE2. The polarity of the output capacitor Cout is then inverted.

In practice, such a DC DC converter is powerful and makes it possible,by providing a plurality of pairs P_(i) of switches similar to P₁, eachassociated with a pair of input and output capacitors Ce_(i), Cs_(i), toobtain the desired voltage level at the output, with an optimal outputratio, with a stress distributed over the various pairs. It will be ofvalue to refer to the text and figures of the aforementioned patent.

In many applications, positive and negative boosted voltages arenecessary. This problem could be solved by the use of two single-voltageoutput converter structures of the prior art as described with referenceto FIGS. 1 a and 1 b, so that one of them supplies a positive boostedvoltage, the other a negative boosted voltage, from the same directcurrent supply low voltage. This technically powerful solution ishowever not optimal in terms of complexity, each single-voltage outputconverter having to retain its own control circuit. Relative to asingle-voltage converter of the same power, a two-converter structurehas a higher cost and reduced reliability.

The invention is an enhancement of the converter described in theaforementioned French patent.

Its object is a topology of a DC DC converter with two output voltages,with a high output ratio, allowing conversion ratios greater than 5, andoptimized in terms of space and performance.

As claimed, the invention therefore relates to a DC DC voltage boostconverter comprising a first and a second input terminals to receive aDC input voltage, an inductive stage connected between the said inputterminals and comprising an inductor connected to a node in series witha switch and at least one first and one second voltage boost structure,characterized in that it comprises:

-   -   a level translator circuit connected between the said node of        the inductive stage and the input terminal connected to the        electric earth and comprising a capacitor connected in series at        a node to a directly connected diode;    -   at least a first boost structure to supply a positive output        voltage between a positive output terminal and an output        terminal connected to the electric earth, the said first        structure being connected between an input node formed by the        said node of the inductive stage and the said positive output        terminal; and comprising a first switch connected to the said        input node, and k_(p) pairs of switches in series, connected in        series between the said first switch and the positive output        terminal, k_(p) being an integer equal to or greater than 1.    -   at least one second boost structure to supply a negative output        voltage between a negative output terminal and the said output        terminal connected to the electric earth, the said second        structure being connected between an input node formed by the        said node of the level translator stage and the said negative        output terminal, and comprising a first switch connected to the        said input node, and k_(n) pairs of switches in series connected        in series between the said first switch and the positive output        terminal, where k_(n) is an integer equal to or greater than 1;    -   k_(p)+1, respectively k_(n)+1 capacitors distributed between a        group of input capacitor(s) and a group of output capacitor(s)        associated with each pair of the first structure, respectively        of the second structure;    -   each pair of switches of the said first and second structure        comprising a first switch and a second switch in series,        controlled simultaneously and alternately one to the open state        and the other to the closed state, the first switches being such        that, in the closed state, they place a group of input        capacitor(s) in series and a group of corresponding output        capacitor(s), and the second switches being such that, in the        closed state, the groups of input and output capacitors are        connected in parallel between the input node of the        corresponding structure and the corresponding positive or        negative voltage terminal;

and the switch of the inductive stage, the said first switch of thesecond structure, the said first switches of the pairs of the firststructure and the said second switches of the pairs of the secondstructure being simultaneously controlled alternately to the open andclosed state, and the said first switch of the first structure, the saidsecond switches of the pairs of the first structure and the said firstswitches of the pairs of the second structure being simultaneouslycontrolled to the opposite state.

Still other objects and advantages of the present invention will becomereadily apparent to those skilled in the art from the following detaileddescription, wherein the preferred embodiments of the invention areshown and described, simply by way of illustration of the best modecontemplated of carrying out the invention. As will be realized, theinvention is capable of other and different embodiments, and it severaldetails are capable of modifications in various obvious aspects, allwithout departing from the invention.

Accordingly, the drawings and description thereof are to be regarded asillustrative in nature, and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWING

FIGS. 1 a and 1 b already described illustrate a single-voltage DC DCconverter according to the prior art, for supplying a positive,respectively negative voltage;

FIG. 2 illustrates a topology of a DC DC converter with two symmetricaloutputs according to the invention, with one pair of additional switchesfor each positive and negative voltage output;

FIG. 3 illustrates a variant, in which the switches are made by diodes;

FIGS. 4 and 5 illustrate the phases corresponding to the off-staterespectively on-state of the switch M;

FIG. 6 illustrates a topology of a DC DC converter with two symmetricaloutputs according to the invention, with three pairs of additionalswitches for each positive and negative voltage output;

FIG. 7 illustrates a topology of a DC DC converter with twonon-symmetrical outputs according to the invention, with a number ofdifferent pairs of switches for each positive and negative voltageoutput;

FIG. 8 illustrates a corresponding basic topology, with an additionalpair of switches;

FIG. 9 illustrates a multi-voltage DC DC converter according to theinvention.

DETAILED DESCRIPTION OF THE DRAWING

FIG. 2 illustrates a topology of a DC DC voltage converter with twoboosted and regulated outputs, a positive voltage output Vs+ and anegative voltage output Vs−, with a second order cell capable ofboosting an input voltage Vin of a determined value, in these two outputvoltages. In a practical example, it has been possible to produce aconverter with a corresponding topology, which, for an input voltage Vinof between 12 and 32 volts, delivers at the output two regulated outputvoltages of more or less 125 volts.

A generator is connected between the input terminals E1 and E2 of theconverter, in order to apply a direct current voltage Vin to itsterminals. E2 is connected to the electric earth.

The converter comprises:

-   -   an inductive input stage connected in parallel between the        terminals E1 and E2, comprising an input inductor Lin in series        with a controlled switch M. The switch M periodically places the        input inductor in parallel with the generator;    -   a first output capacitor Cout+ connected in parallel        respectively to output terminals Outp and Out, supplying at its        terminals a positive output voltage Vs+; the output terminal Out        being connected with the input terminal E2 to the electric        earth;    -   the second output capacitor Cout− connected in parallel        respectively between output terminals, Out and Outn, supplying        at its terminals a negative output voltage Vs−;    -   a voltage level translation circuit, connected in parallel to        the said controlled switch M, between a connection node N1        corresponding to the mid-point between the input inductor and        the controlled switch M, and the terminal E2 connected to the        electric earth. This circuit comprises a capacitor Ct and a        diode Dt connected in series; a terminal of the capacitor is        connected to the node N1. The cathode of the diode Dt is        connected to the terminal E2, the nodes N1 and N2 forming        respectively an input node for a positive, respectively negative        voltage boost structure;    -   a positive voltage boost structure, connected between the input        node N1 and the output terminal Outp;    -   a negative voltage boost structure, connected between the input        node N2 between the capacitor and the diode of the level        translation circuit and the output terminal Outn.

The switches are typically made by semiconductor transistors such as forexample, and not limitingly, MOS or bipolar transistors.

In the example illustrated in FIG. 2, these structures each form asecond order voltage boost cell, with three switches and two elementarycapacitors of the same value, that are:

-   -   either in series between the input node of the structure in        question and the output terminal not connected to the earth, via        one of the switches in the closed state simultaneously with the        switch M;    -   or in parallel, the other two switches being closed and the        switch M open.

More precisely, the first structure that supplies the positive outputvoltage Vs+ between the terminals Outp and Out comprises:

-   -   a first controlled switch SHp0, of which one terminal is        connected to the corresponding input node N1 of the structure,        and a pair of switches in series SBp1, SHp1. This assembly is        connected at the input to the other terminal A1 of the first        switch SHp0 and at the output to the output terminal Outp not        connected to the electric earth;    -   an elementary capacitor Cp connected in series between the        mid-point A2 between the two switches of the pair SBp1, SHp1 and        the input node N1 of the structure; and an elementary capacitor        Cp of the same value connected in parallel to this pair SBp1,        SHp1, that is to say between the output terminal Outp not        connected to the electric earth and the terminal A1 of the first        switch SHp0;    -   the control signal S1 controls the switches SHp0 and SHp1 and        the control signal S2 controls the switches M and SBp1.

In a similar manner, the second structure which supplies the negativeoutput voltage Vs− between the terminals Outn and Out comprises:

-   -   a first controlled switch SBn0, of which one terminal is        connected to the corresponding input node N2 of the structure,        and a pair of switches in series SBn1, SHn1, connected at the        input to the other terminal B1 of the first switch SBn0 and at        the output to the output terminal Outn not connected to the        electric earth, and    -   an elementary capacitor Cn connected in series between the        mid-point B2 between the two switches of the pair SBn1, SHn1 and        the input node N2 of the structure; and an elementary capacitor        Cn of the same value connected in parallel to this pair SBn1,        SHn1, that is to say between the output terminal Outn not        connected to the electric earth and the terminal B1 of the first        switch SBn0;    -   the control signal S1 controls the switch SHn1 and the control        signal S2 controls the switches M, SBn0 and SBn1.

The switches SBpi, SHpi, SBni, SHni may be advantageously made bydirectly connected diodes DBpi, DHpi, DBni, DHni, as illustrated in FIG.3. Only the switch M of the inductive stage remains. This simplifies theconnection and makes it possible to use only one control signal S2 toplace this switch alternately in the open and on state depending on thecyclic ratio α=Ton/Ton+Toff.

The operation of the converter is such that the user has simultaneouslya resonant circuit in one structure, while in the other structure, thecapacitors Cp or Cn are charged in parallel. The operation of eachstructure alternates according to the alternately open and closed stateof the switch M. Each resonant circuit forms a series circuit comprisingthe capacitors Cp or Cn, and the switch or the diode that connects themin series DBp1 or DHn1, between the input point of the structure inquestion N1 or N2 and the output not connected to the earth (FIG. 3).

In the two structures, each pair may also comprise, advantageously, arecovery inductor, as seen in relation with the description of the priorart with reference to FIGS. 1 a and 1 b. In the figures thereforeinductors Lrp and Lrn are provided. These recovery inductors make itpossible to improve the output ratio of the two-voltage converter, asdetailed in the description of the prior art with reference to the citedFrench patent. In the first structure, an inductor Lrp is placed on theconnection path in series of the two elementary capacitors Cp. In thesecond structure, an inductor Lrn is placed on each of the charge pathsin parallel of the two elementary capacitors Cn.

The operation of the converter is in greater detail as follows:

-   -   the voltage at N1 varies between 0 and ½Vs+: the voltage is        equal to 0 when the switch M is controlled to the closed state;        and at ½Vs+ when the switch M is controlled to the open state.        The voltage at the terminals of each capacitor is ½Vs+. At the        terminals of the capacitor Ct of the voltage translator stage,        the voltage is direct current. Therefore, the voltage at N2        varies between—½ Vs (when N1 is at 0) and 0 (when N1 is at ½Vs).

When the switch M is controlled to the open state, N1 goes to ½Vs+. Thecurrent in the inductor Lin is divided at the node N1 into two: oneportion enters the “positive” structure, and allows the charge via Cp,SHp1 (or DHp1) and SHp0 (or DHp0), Cp. The other passes via Ct anddischarges the resonant circuit Ct, Cn, SHn1 (or DHn1), Cn and againpasses partly into the diode Dt. The equivalent electric diagram for thecase in which the transistors of the structures are diodes, as seen inFIG. 3, is illustrated in FIG. 4.

When the switch is controlled to the closed state, N1 returns to zero:this discharges the resonant circuit Cp, Sbp1 (or Dbp1), Cp of thepositive structure, and charges in the second structure via Cn, SHn0 (orDHn0), Ct and SBn1 (or DBn1), Cn, Ct. The equivalent electric diagram isillustrated in FIG. 5 for the case in which the transistors of the twostructures are diodes (FIG. 3).

This gives an equal distribution of the current in the various chainsthat are symmetrical.

Finally, symmetrical voltages Vs+=−Vs− are obtained at the output.

It will be noted that in the advantageous case, and as illustrated, inwhich recovery inductors Lrn, Lrp, are provided, it involves in practiceinductors of very small values, whose only function is to provide anenergy rebalancing without losses in the various capacitors.

The capacitor Ct is in practice dimensioned relative to the negativestructure, according to the number k_(n) of pairs of additionalswitches: Ct≧k_(n).Cn. In the example of FIG. 2, this number k_(n) isequal to 1 and Ct is chosen to be greater than or equal to an elementarycapacitor Cn.

FIG. 6 illustrates a generalization of a dual-voltage converteraccording to the invention, with several pairs of switches (diodes inthe example) in each voltage boost structure, in order to form, withgroups of associated input and output capacitors, an equal number ofvoltage boost cells.

The positive structure that supplies at the output a positive voltageVs+ between the terminals Outp and Out, is connected to the input nodeN1. It comprises:

-   -   a first controlled switch SHp0, connected between the        corresponding input node N1, and a node A1;    -   a series set of k_(p) pairs of switches in series (SBpi, SHpi),        k_(p) being an integer greater than or equal to 1. This set is        connected between the node A1 and the output terminal Outp not        connected to the electric earth;    -   k_(p)+1 capacitors per pair, divided into a group of input        capacitor(s) Gini, and a group of output capacitor(s) Gouti, and        attached to each pair of switches of rank i in the series set.        More precisely, the pair connected to the node A1 is the pair of        rank 1 by convention; the input group comprises i elementary        capacitors Cp of the same value connected in series between the        mid-point A′i between the two switches of the pair in question        of rank i and the input node N1 of the structure; and the output        group comprises (k_(p)+1)−i elementary capacitors of the same        value Cp connected in series between the connection node Ai of        the pair in question of rank i with the next pair of rank i+1,        and the output terminal Outp. This therefore gives, attached to        the first pair (SBp1, SHp1), of rank i=1 with the adopted        convention, an input group Gin1 comprising one elementary        capacitor Cp connected between A′1 and N1, and an output group        Gout1 comprising three elementary capacitors Cp connected        between A1 and Outp; to the second pair (SBp2, SHp2), of rank        i=2, an input group Gin2 comprising two elementary capacitors Cp        connected between A′2 and N1 and an output group Gout2        comprising two elementary capacitors Cp connected between A2 and        Outp; to the third pair (SBp3, SHp3), of rank i=3, an input        group Gin3 comprising three elementary capacitors Cp connected        between A′3 and N1 and an output group Gout3 comprising one        elementary capacitor Cp connected between A3 and Outp.

The negative structure that supplies at the output a negative voltageVs− between the terminals Outn and Out, is connected to the input nodeN2. It comprises in a dual manner:

-   -   a first controlled switch SBn0, connected between a node B1 and        the corresponding input node N2;    -   a series set of k_(n) pairs of switches in series (SBni, SHni),        k_(n) being an integer greater than or equal to 1 connected        between the output terminal not connected to the earth Outn and        the node B1;    -   k_(n)+1 capacitors associated with each pair and divided into a        group of input capacitor(s) G′inj, and a group of output        capacitor(s) G′outj, attached to each pair of switches of rank j        in the series set, and taking by convention j=1 for the first        pair (SBn1, SHn1) connected to the node B1. The input group        G′inj comprises j elementary capacitors Cn of the same value        connected in series between the mid-point B′j between the two        switches of the pair in question of rank j and the input node N2        of the structure; and the output group G′outj comprises        (k_(n)+1)−j elementary capacitors Cn of the same value connected        in series between the connection node Bj of the pair in question        of rank j with the next pair of rank i+1 and the output terminal        Outn.

In the other two structures, each pair advantageously comprises arecovery conductor Lrn for the first structure, Lrp for the second,which improves the output ratio of the dual-voltage converter.

The switches of each pair of the two structures are simultaneously onecontrolled to the on-state (closed) and the other to the open state. Allthe switches SHpi or SHni are controlled by the same control signal S1and all the switches SBpi and SBni and the switch M of the inductivestage are controlled by the same control signal S2, the control signalsS1 and S2 being complementary, as explained with reference to FIG. 2.

In a practical embodiment, and as illustrated, the switches SHpi, SHni,SBpi and SBni are made by directly connected diodes, as already seenwith reference to FIG. 3. This then gives a single line of controlsignal S2 to the switch M of the inductive stage, which simplifies theconnector technology.

In the positive structure, the operation is as follows: when the switchM is closed for a time Ton, the input capacitors of each pair are inseries with the output capacitors of each pair. When the switch M isoff-state (open) for a time Toff, the input capacitors of each pair areconnected to the terminal E1 through the input inductor in parallel withthe output capacitors of this pair.

This gives the dual operation on the second structure.

In practice, the capacitor Ct of the voltage translation stage isdimensioned according to the number of elementary capacitors of thesecond structure: Ct≧k_(n).Cn, where k_(n) is the number of pairs of thestructure.

FIG. 7 illustrates the case of a non-symmetrical dual-voltage converter,that is to say where the number k_(p) and k_(n) of pairs of additionalswitches are not equal. In the example, k_(p)=1 and k_(n)=2.

FIG. 8 illustrates the case of a converter with a first order boostcell, with no pairs of additional switches.

In these figures, and as shown in FIG. 6, the physical arrangement ofthe switches and capacitors is not without importance. It is shown thatit allows an optimal practical embodiment in terms of occupation ofsurface area and of connection reliability. In this arrangement, thesuccessive switches or diodes in the structures are placed like a stepladder and the capacitors are aligned on either side relative to thesesteps in a triangular network.

Furthermore, it is possible to connect the capacitors having the samevoltage at their terminals, as illustrated in dashed lines in FIG. 6.

It will be noted that the invention is not limited to a positivestructure and a negative structure associated with an inductive stageand a voltage level translation stage. It is possible to connect aplurality of positive structures to the node N1, to supply a pluralityof positive voltages Vs+₁, Vs+₂, etc., and/or a plurality of negativestructures to the node N2, to supply a plurality of negative voltagesVs+₁, Vs+₂, etc., as illustrated schematically in FIG. 9. In a variantnot illustrated, each negative structure has its own level translationstage. The limits of practical embodiment are essentially of atechnological and dimensional nature.

It will be readily seen by one of ordinary skill in the art that thepresent invention fulfils all of the objects set forth above. Afterreading the foregoing specification, one of ordinary skill in the artwill be able to affect various changes, substitutions of equivalents andvarious aspects of the invention as broadly disclosed herein. It istherefore intended that the protections granted heron be limited only bythe definition contained in the appended claims and equivalent thereof.

1. A DC DC voltage boost converter comprising a first and a second inputterminals to receive a direct input voltage, an inductive stageconnected between said input terminals and comprising an inductorconnected to a node in series with a switch, and at least one first andone second voltage boost structure, comprising: a level translatorcircuit connected between said node of the inductive stage and the inputterminal connected to the electric earth and comprising a capacitorconnected in series at a node to a directly connected diode; at least afirst boost structure to supply a positive output voltage between apositive output terminal and an output terminal connected to theelectric earth, said first structure being connected between an inputnode formed by said node of the inductive stage and said positive outputterminal; and comprising a first switch connected to said input node,and k_(p) pairs of switches in series, connected in series between saidfirst switch and the positive output terminal; k_(p) being an integerequal to or greater than 1; at least one second boost structure tosupply a negative output voltage between a negative output terminal andsaid output terminal connected to the electric earth, said secondstructure being connected between an input node formed by said node ofthe level translator stage and said negative output terminal, andcomprising a first switch connected to said input node, and k_(n) pairsof switches in series connected in series between said first switch andthe positive output terminal, where k_(n) is equal to or greater than 1;k_(p)+1, respectively k_(n)+1 capacitors distributed between a group ofinput capacitor(s) and a group of output capacitor(s) associated witheach pair of the first structure, respectively of the second structure;each pair of switches of said first and second structures comprising afirst switch and a second switch in series, controlled simultaneouslyand alternately one to the open state and the other to the closed state,the first switches being such that, in the closed state, the firstswitches place a group of input capacitor(s) in series and a group ofcorresponding output capacitor(s), and the second switches being suchthat, in the closed state, the groups of input and output capacitors areconnected in parallel between the input node of the correspondingstructure and the corresponding positive or negative voltage terminal;and the switch of the inductive stage, said first switch of the secondstructure, said first switches of the pairs of the first structure andsaid second switches of the pairs of the second structure beingsimultaneously controlled alternately to the open and closed state, andsaid first switch of the first structure, said second switches of thepairs of the first structure and said first switches of the pairs of thesecond structure being simultaneously controlled to the opposite state.2. The converter according to claim 1, wherein the switches of thestructures are directly connected diodes.
 3. The converter according toclaim 2, wherein each pair comprises a recovery inductor.
 4. Theconverter according to claim 2, in that it comprises a plurality offirst structures and/or of second structures connected in parallelbetween the input node and the corresponding voltage terminal, in orderto supply a plurality of positive output voltages and/or negative outputvoltages.
 5. The converter according to claim 2, further comprising aplurality of level translation circuits, each one associated with asecond respective structure.
 6. The converter according to claim 2,wherein in each structure, the first switch and the switches of thepairs are placed in series according to a step ladder design, and theelementary capacitors of the input and output groups are placed oneither side and aligned on either side relative to said steps in atriangular network.
 7. The converter according to claim 1, wherein eachpair comprises a recovery inductor.
 8. The converter according to claim7, in that it comprises a plurality of first structures and/or of secondstructures connected in parallel between the input node and thecorresponding voltage terminal, in order to supply a plurality ofpositive output voltages and/or negative output voltages.
 9. Theconverter according to claim 7, further comprising a plurality of leveltranslation circuits, each one associated with a second respectivestructure.
 10. The converter according to claim 7, wherein in eachstructure, the first switch and the switches of the pairs are placed inseries according to a step ladder design, and the elementary capacitorsof the input and output groups are placed on either side and aligned oneither side relative to said steps in a triangular network.
 11. Theconverter according to claim 1, in that it comprises a plurality offirst structures and/or of second structures connected in parallelbetween the input node and the corresponding voltage terminal, in orderto supply a plurality of positive output voltages and/or negative outputvoltages.
 12. The converter according to claim 11, wherein in eachstructure, the first switch and the switches of the pairs are placed inseries according to a step ladder design, and the elementary capacitorsof the input and output groups are placed on either side and aligned oneither side relative to said steps in a triangular network.
 13. Theconverter according to claim 1, further comprising a plurality of leveltranslation circuits, each one associated with a second respectivestructure.
 14. The converter according to claim 13, wherein in eachstructure, the first switch and the switches of the pairs are placed inseries according to a step ladder design, and the elementary capacitorsof the input and output groups are placed on either side and aligned oneither side relative to said steps in a triangular network.
 15. Theconverter according to claim 1, wherein in each structure, the firstswitch and the switches of the pairs are placed in series according to astep ladder design, and the elementary capacitors of the input andoutput groups are placed on either side and aligned on either siderelative to said steps in a triangular network.